Conventionally, as shown in paragraph [0110] and the like of Japanese Unexamined Patent Application Publication No. 2015-114386, a moisture permeation amount measuring apparatus (e.g., a water vapor permeability measuring apparatus “PERMATRAN” manufactured by MOCON, Inc., etc.) for instantly measuring moisture permeability of a sample with high accuracy has been used. Using this type of apparatus enables measurement of the amount of moisture permeating various samples, such as a single film and a multilayer film having a multilayer laminated structure.
For example, a polarizing plate is a multilayer film in which a base film, a polarizer, an adhesive layer, and the like are laminated. A polarizing plate potentially has low durability in a wet heat test, and the moisture permeability and moisture amount in each layer thereof are very important. Each layer constituting a polarizing plate has its own moisture permeability, and when each layer is individually measured using a moisture permeation amount measuring apparatus, the moisture permeability of each layer can be calculated. It has been thought that durability of a polarizing plate in which these layers are laminated can be estimated in design based on the moisture permeability and moisture amount of each layer.
However, in a process of studying durability of a polarizing plate for wet heat, the inventors of the present invention have found that moisture permeability of each layer constituting the polarizing plate is different between in a single layer state and in a laminated state. It is considered that this is caused by receiving interaction such as internal pressure due to difference in linear expansion of each of the laminated layers and existence of internal stress caused through a stretching process.
In a conventional moisture permeation amount measuring apparatus, it is impossible to analyze moisture permeability of each layer in a multilayer film, such as a polarizing plate, in a state where each layer is laminated. Therefore, this does not enable analysis of characteristics (moisture permeability and moisture amount) of each layer of a multilayer film used while each layer is laminated in a state Where the multilayer film is actually used. In addition, the conventional moisture permeation amount measuring apparatus can only measure moisture permeability of not only the multilayer film but also a sample, and thus it is difficult to widely analyze moisture permeability of a sample when a water vapor concentration is changed (hereinafter referred to as also “dynamic moisture permeability”).
Further, such a problem is a new problem that arises not only in the case of analyzing dynamic moisture permeability of a sample when water vapor is used as a specimen, but also in the case of analyzing dynamic gas permeability of a sample when another specimen gas such as oxygen, carbon dioxide, or the like is used.
The present invention has been made in light of the above-mentioned circumstances, and it is an object of the present invention to provide a dynamic moisture permeability evaluation apparatus, a method for evaluating dynamic moisture permeability, and a dynamic moisture permeability evaluation program, capable of widely analyzing characteristics of a sample. Another object of the present invention is to provide a dynamic moisture permeability evaluation apparatus, a method for evaluating dynamic moisture permeability, and a dynamic permeability evaluation program, capable of evaluating characteristics in any layer in a sample.